The role of Eikenella corrodens, Fusobacterium nucleatum, and Wolinella recta as pathogens associated in destructive periodontal disease has been described in a number of studies using culture based assay systems. The standard culture methods are inadequate for the routine diagnosis of these pathogens. By developing DNA probe-based assays for the detection of these pathogens, it would be practical to deliver diagnostically valuable information to the dental practitioner on a routine basis. DNA probes for the detection of target DNA from these organisms will be developed by isolation of whole genomic sequences or species- specific segments and use in a standard membrane hybridization assay. Conventional radio-labelling, novel sample preparation and hybridization, and recombinant DNA technology will be employed. Phase II objectives will involve clinical studies and non-isotopic methodology. The long term objective is to provide a rapid, sensitive and accurate diagnostic battery of DNA probes for the detection of periodontal disease for commercial application.